This disclosure relates to fire retardant materials, and, more particularly, to moldable intumescent compositions. Intumescent compositions are generally fire retardant composite compounds that swell and form ceramic-like sponges when exposed to the high temperatures. Intumescent compositions can be applied in the form of coatings or paints or they may be formed into mat-like structures that may be placed within or around an apparatus exposed to or operating under high temperatures.
Intumescent compositions are generally used on the wall surfaces of buildings, ships, aircraft, motor vehicles, or other vessel. The nature of the composition allows its thickness to be kept at a minimum until it is activated by high temperatures. The composition, upon being subjected to such activation temperatures (e.g., temperatures greater than 350xc2x0 C.), gives off gases and at the same time undergoes molecular changes, which results in a foamed matrix and a change in physical properties such as the formation of incombustible or low combustible residues that have a reduced ability to conduct heat. In many instances, a major part of the residue formed is a carbonaceous material that is formed by decomposition of the matrix polymer or the dehydration of a polyhydric substance such as a polyalcohol incorporated into the composition for that purpose. Reactions occur within the intumescent composition so that when the composition is heated to beyond a specific activation temperature, components (such as the polyhydric alcohol, ammonium hydrogen phosphate or hydrated magnesia) within the composition are decomposed, thereby generating water, carbon dioxide, ammonia, and/or other heat absorbing gases that do not readily support combustion.
Intumescent compositions can be applied in the form of coatings or mat-like structures. Intumescent coatings however, require a lengthy and complicated process for their application to a surface. Oftentimes, a primer is required to promote adhesion to the surface, and a drying time of several hours may be needed. When these coatings become intumescent after exposure to elevated temperatures, the coatings are transformed into a weak sponge with a limited life.
Mat-like structures can be used in place of coatings to avoid some of the problems associated with the coatings. In the mat-like structures, multiple layers of fire resistant materials having intumescent materials located therebetween are used to provide a flexible wrap that provides stability to expanded intumescent materials. These flexible wraps generally include alternating layers of fire resistant materials and intumescent materials that are designed to expand to provide a consistent and effective fire protection system. Although mat-like structures can be manufactured to have sufficient flexibility that allows them to conform to the shape of the object to be protected (e.g., conduits, electrical cable, etc.), they tend to require additional hardware or an adhesive in order to be held into place. The additional hardware and the use of adhesives, adds to the complexity and costs associated with this use.
Disclosed herein is an intumescent composition, an intumescent additive mixture for forming the intumescent composition, methods for forming the intumescent composition, articles made from the intumescent composition, intumescent additive mixture, and reaction products of the intumescent composition and the intumescent additive mixture. In one embodiment, the intumescent composition comprises a halogenated polymer, antimony oxide, and intercalated graphite. In one embodiment of the intumescent additive mixture, the mixture comprises antimony oxide and intercalated graphite.
One embodiment of the method of making an intumescent composition comprises melt blending a halogenated polymer with antimony oxide, and intercalated graphite.
These and other features will become better understood from the detailed description that is described in conjunction with the accompanying drawings.